Businesses or other entities having a need for volume printing typically purchase a production printer. A production printer is a high-speed printer used for volume printing (e.g., one hundred pages per minute or more). Production printers are typically continuous-forms printers that print on webs of print media that are stored on large rolls.
A production printer typically includes a localized print controller that controls the overall operation of the printing system, and a marking engine (sometimes referred to as an “imaging engine” or as a “print engine”). The marking engine includes one or more printhead assemblies, with each assembly including a printhead controller and a printhead (or array of printheads). An individual printhead includes multiple tiny nozzles (e.g., 360 nozzles per printhead depending on resolution) that are operable to discharge ink as controlled by the printhead controller. A printhead array is formed from multiple printheads that are spaced in series across the width of the print media.
When in operation, the web of print media is quickly passed underneath the printhead arrays while the nozzles of the printheads discharge ink at intervals to form pixels on the web. In order to ensure that ink does not partially dry within the printheads during printing (which would adversely affect print quality), flush lines are printed at page boundaries on the web. These flush lines are used to flush ink from the nozzles on a regular basis to ensure that the ink does not become overly viscous.
To reduce the visual footprint of individual flush lines, all of the nozzles located at a single horizontal position along a width of the web may be discharged at the same vertical location along the height of the web. This means that, at a single physical location, the web is saturated with a great deal of ink. For example, in cyan, magenta, yellow, and black (CMYK) printing systems, a C, M, Y, and K nozzle may each discharge a droplet at the same physical pel location on the page. This is repeated across the entire width of the page. These flush lines have a small overall size, but may oversaturate the web with ink, which can cause warping or distortion of the web, or even can smear or offset the ink to different portions of the printed page.